I didn't know most of this.
Totally seamless Android to Android, and the videos are normal quality. And what are the multiple places to update core functionality of the phone? I get updates periodically, and I honestly have my doubts about whether any other place to check could really include "core functionality", but maybe there's another place for something about how it interacts with iPhones.
I tend not to send/receive a lot of videos, but the biggest problem I've had connecting between Android and iPhone was really more about the fact that I used to have an iPhone. When I switched, most things worked fine, but I stopped receiving texts from a few other iPhone users. I'd only notice I had missed anything, in most cases, days later when I opened up my Mac computer, and the iMessages would pour in that I never received on the phone. I kept telling these people to change their settings to send me regular texts rather than iMessages, but it turned out there was a setting I needed to change in my Apple account to disable "use iMessage". After that change, they all started coming to my phone like any other texts, but Apple definitely could have made that transition easier (if they cared to) by automatically sending these as texts if the user hadn't had an iPhone online in some time. If I hadn't still had a Mac computer, I might never have known about many of these, and people might have just thought I was ignoring them!